It is known in the air valve art to provide valves which can be employed in stacks. Heretofore stackable air valves have been provided which include flow control valves in exhaust ports. However, it has not been possible heretofore to provide a stacking body which will provide a four-way stacking valve with a stacking body provided with a separate flow control valve for each exhaust passage, between a common exhaust outlet passage and each exhaust chamber in the main valve spool bore, and with a common electrical conduit so as to permit a solenoid to be electrically connected to the air valve with one connection at each individual valve in a stack of valves. Flow control valves have been used before in exhaust ports in more complicated structures, as in U.S. Pat. Nos. 2,912,007 and 2,993,511.